In cylinders of in internal combustion engines combustion characteristics such as efficiency, ignition, and knock are affected by intake airflow patterns. Tumble and swirl patterns characterize different aspects of the turbulence in the cylinder. Tumble and swirl ratios are terms used to quantify these flow patterns. Tumble ratio is defined as the strength of horizontal recirculation of the intake gas in the cylinder while swirl ratio is defined as the strength of vertical recirculation in the cylinder. Tumble and swirl patterns have different influences on various aspects of combustion (e.g., ignition, knock, efficiency, emissions, power, etc.) In previous engines, intake ports are designed to provide set tumble and swirl flow patterns. Therefore, the set patterns in the combustion airflow can negatively impact combustion when the engine is run outside of the ideal operating conditions for the set flow patterns. Attempts have been made to dynamically adjust the tumble and swirl flow patterns for different operating conditions in an engine system with a rotatable flow plate extending into an intake conduit.
However, this type of system only marginally alters airflow patterns and does not enable desired amount of swirl and tumble to be generated within the cylinder during certain operating conditions.
To address at least some of the aforementioned problems, an engine system is provided. The engine system includes a rotatable intake port circumferentially surrounding at least a portion of a stem of an intake valve coupled to a cylinder, the rotatable intake port having a first curved section extending inward toward or outward from a rotational axis of the rotatable intake port. The engine system further includes an intake port actuator coupled to the rotatable intake port configured to rotate the rotatable intake port about the rotational axis based on engine operating conditions. The curved contours of the adjustable intake port are designed to change the turbulence of air entering the cylinder to improve combustion efficiency, reduce knock, increase power, and/or decrease emissions, across a wide range of operating conditions. Thus, the curved intake port section can be rotated to generate a strong imbalance in airflow around an intake valve head to provide desired levels of turbulence in the cylinder that best suit the current operating conditions, if desired.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.